Abstract:

To accurately capture the parameter variability induced by the spatial heterogeneity of jointed rock masses, a typical itabirite rock mass in a West African mine was investigated. By combining joint orientation data, spatial cluster analysis was conducted for identifying dominant joint sets, and laboratory tests for parameter calibration were performed to build a 3DEC-based discrete equivalent model. Through a combined analysis of uniaxial compression simulations and the coefficient of variation of mechanical parameters, the REV of the rock mass was determined. Based on this, direct shear numerical experiments were conducted under different shear directions. The results indicate that the spatial configuration of joints significantly influences the rock mass's shear strength. As the normal stress increases from 3 MPa to 5 MPa and then 10 MPa, the shear stress in the X-direction increases by 56% and 90%, while the shear stress in the Y-direction increases by 48% and 102%. Under normal stresses of 3, 5, and 10 MPa, the shear stress in the Y-direction is 32%, 14%, and 20% higher than that in the X-direction, respectively. During the shearing process, the displacement field exhibits multi-directional and non-uniform evolutionary characteristics, with the shear stress direction serving as the dominant orientation of deformation.

Key words: jointed rock mass, representative elementary volume (REV), coefficient of variation, shear strength, shear deformation